Modem commercial buildings include an abundance of communications equipment. Individual offices within the building are often equipped with telephones and fax machines, as well as computers that are interconnected with other computers through high speed communication networks. For ease of administration, apparatus for interconnecting such equipment (with each other and with outside networks) is centralized via interconnection (cross-connect) panels that serve the entire building.
A typical cross-connect panel includes several 110-type connector blocks each having an array of insulation displacement connectors (IDCs) for terminating large bundles of telephone wires. IDCs are commercially available and designed to facilitate making mechanical and electrical connection to a wire--particularly a wire that is surrounded by dielectric insulation. Each IDC includes a pair of opposing contact fingers that strip insulation from a wire that is pressed between the contact fingers so that an electrical contact is made between the wire and the IDC. Each IDC accommodates a single wire pressed between its opposing contact fingers, and is so compact that many IDCs can fit into a small area.
Several arrays of IDCs may be used to terminate a bundle of wire from a telephone central office while other arrays on the cross-connect panel may be used to terminate bundles of wire from telephone equipment within the building. Interconnecting particular wires from one bundle with particular wires from another bundle is accomplished with a patch cord comprising a cord with a plug (patch plug) attached to each end. The cord includes several wires within a plastic jacket. The patch plugs include a number of contact blades that are designed to be pressed into an equal number of IDCs within an array thereof. Once wired, a patch plug is a multiple wire connector that may be installed and removed from the cross-connect panel for the purpose of branching off existing lines or connecting together discrete areas of the terminal field.
One type of patch plug used in connection with the 110-type connector block is described in U.S. Pat. No. 5,226,835, which is incorporated herein by reference. The patch plug includes a two-piece dielectric housing which snaps together and captures several conductors therein. Each of the conductors includes an insulation displacement connector at one end for receiving individual wires from a cord and a contact blade at the other end for inserting into the IDCs of the 110-type connector block. A cord comprising a bundle of insulated wires, surrounded by an insulating jacket, is prepared for connection to the conductors by stripping away a small portion of the jacket to expose the insulated wires. The insulated wires may then be placed into the underside of the upper housing member which includes narrow channels for holding the wires in fixed positions. Thereafter, the upper housing member may be snapped onto the lower housing member by pressing them together. The wires are then collectively pressed/seated into the IDCs of the conductors. A disadvantage of this type of patch plug is that the IDCs are exposed and may be damaged or bent either before or during assembly. In addition, because termination tools may damage the exposed contacts, termination is typically done by hand, which can result in inefficiencies and excessive waste.
Another type of patch plug is described in U.S. Pat. No. 5,460,545. This patch plug includes an insulative plastic housing having three separable parts, a lower first housing, an upper second housing and a contact insulator housing. The patch plug also includes a plurality of connector contacts in the insulator housing, each contact having an IDC at one end and a blade portion at the other end. As with the previous patch plug, the IDCs of the contacts are exposed and subject to damage.
Both of the above mentioned patch cords also present additional difficulties. First, since the patch cords are limited in width size to permit installation of adjacent patch cords to the 110-type connecting block without missing terminal locations that may require access, a very tight clearance exists between the endmost insulation displacement connectors of the contacts and the side walls of the patch plug housing, inhibiting the use of a contact protection block around the connectors. Second, since the wires remain in the housing, they must be carefully trimmed, adding to installation time and the increased possibility of error. Failure to adequately trim can result, among other things, in wires being jammed between the termination cap and the rest of the housing, preventing proper termination. Third, it is difficult to remove these patch plugs once they are mounted to a termination block, especially when several patch plugs are mounted side-by-side, since it is difficult to build up a sufficient grasping force on the upper and lower surfaces of the plug housing when attempting to pull the plug out.
In view of the above, it should be appreciated that there is still a need for a patch plug that may be readily installed in the field by hand or by a punchdown tool and that may be readily removed and reinserted at a different location on the cross-connect panel having IDCs that are protected from damage.